1. Field of the Invention
The invention relates to an adhesive tape preferably for wrapping elongate product such as more particularly leads or cable looms, having a textile carrier and having a preferably pressure-sensitive adhesive coating applied at least to one side of the carrier. The invention further relates to the use of the adhesive tape and also to an elongate product such as a cable harness which is jacketed with the adhesive tape of the invention, and to the textile carrier itself.
2. Description of Related Art
Adhesive tapes have long been used in the industry for producing cable harnesses. In this utility, the adhesive tapes serve to bundle a multiplicity of electrical leads prior to installation or in the as-installed state, in order to reduce, by bandaging, the space taken up by the bundle of leads, and also, in addition, to obtain protective functions.
Also in use are jackets which consist of a covering, the self-adhesively treated adhesive tape being present at least in an edge region of the covering and being bonded to the covering in such a way that the adhesive tape extends over one of the longitudinal edges of the covering, preferably in an edge region which is narrow in comparison to the width of the covering. A product of this kind, and also optimized embodiments thereof, is disclosed in EP 1 312 097 A1. These jackets are known to the skilled person by the designation of “sleeves”.
The carriers of these adhesive tapes/sleeves are mostly textile and consist predominantly of PET. Used typically for this purpose as carriers is woven or nonwoven PET fabric which has been coloured black.
In the wake of the increasing introduction of hybrid cars, the adhesive tapes/sleeves are now required additionally to fulfil a warning function: all cables or cable bundles with voltages greater than 60 V must be marked by an orange shade. In the course of the year 2010, the shade stipulated as the standard shade in this context was RAL 2003 (pastel orange).
To date there have been no solutions for orange adhesive tapes/sleeves which exhibit no significant colour fade after a test duration of 3000 hours even at temperatures of 125° C. or 150° C.
One possible consequence of this in practice is that a fire-fighter, confronted with an older car that has been involved in an accident, may not be protected by a bright orange warning signal from cables which are carrying high voltages.
The testing and classifying of adhesive tapes for cable jacketing take place in the motor vehicle industry in accordance with extensive bodies of standards, such as, for example, LV 312-1 “Protection systems for wire harnesses in motor vehicles, adhesive tapes; test guideline” (October 2009), as a joint standard of the companies Daimler, Audi, BMW and Volkswagen, or the Ford specification ES-XU5T-1A303-aa (revised version March 2011) “Harness Tape Performance Specification”. In the text below, these standards are referred to in abbreviated form as LV 312 and Ford specification, respectively.
The influence of elevated temperature over prolonged time periods must not cause adhesive tapes/sleeves to decolour, bleach or fade. Furthermore, the cable insulation must not undergo alteration, let alone damage, by the influence of the adhesive tape in combination with elevated temperature over prolonged time periods—compatibility with the core insulation is a must. The core insulation must not exhibit any discoloration, cracking or other damage.
LV 312 here distinguishes between four temperature classes, T1 to T4, corresponding to 85° C. (also called temperature class A), 105° C. (also called temperature class B (105)), 125° C. (also called temperature class C) and 150° C. (also called temperature class D), which the wrapped cables are required to withstand for 3000 hours. It is obvious that temperature classes T3 and T4 impose more exacting requirements on the adhesive tape than the lower classes T1 and T2. Classification as T1 to T4 is determined both by the cable insulation material and also by the pressure-sensitive adhesive and type of carrier.
EP 1 607 459 B1 discloses the spin dyeing of PET textile carriers. The textile carrier consists of spundyed threads or fibres. In spin dyeing, a polymer used for producing fibres is initially melted. To produce a spinning dope, additives such as antioxidants and colour pigments are added to the polymer melt. The spinning dope which is used for producing the fibres is coloured directly. The dope is subsequently spun by means of an extruder and further processed to form yarns or staple fibres. It is preferred in that patent if, by using spundyed yarns or fibres as carrier material of the adhesive tape, the dye is already incorporated into the polymeric matrix in the course of the operation of producing the fibres themselves, in such a way that there can be no decolouring of the textile material or any dye migration later in the course of storage or exposure of the adhesive tape at elevated temperatures.
However, the assertions made in this patent application apply in general only to black dyeing, since the black colour particles in question have no tendency to fade at high temperatures.
In the case of spundyed and stabilized fibres, fading occurs as a result of temperature exposure, through degeneration of the colour pigment/dye, if orange-coloured particles (for example, as pure orange or as a mixture of red, yellow and pure orange) are used. Furthermore, in view of the high cost and complexity involved in equipping for spin dyeing for a single colour, very high batch sizes must be manufactured in order to obtain a cost-effective operation.
Currently available on the market, then, are tesa® 51026 orange (piece-dyed, light) and tesa® 51026 orange (spundyed, dark). The carriers of both products contain standard orange pigments with azo compounds, and their tendency to decolour under temperature exposure is such that they attain the temperature class only of T2 (105° C. for 3000 hours). By comparison of temperature storage results on the one hand only for the carrier and on the other hand for the carrier coated with adhesive and bonded to aluminium, it is possible to ascertain, for both forms of colouring, that in terms both of fading and of migration there is no difference in temperature stability above T2.
It is an object of the invention to obtain a marked improvement over the prior art and to provide an adhesive tape with a coloured textile carrier, and also to provide a coloured textile carrier, which have no tendency to fade even on elevated temperature exposure.